Sequential Mixing for Crude Oil Desalting
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Solution Overview
Problem
Desalting heavy crude oil in refinery systems is challenging due to its high viscosity and density, leading to stable emulsions that are difficult to break, resulting in inefficient salt removal and corrosion issues.
Innovation Solution
A sequential mixing process involving a mixing valve and a coalescer mixer, where the crude oil and wash water are mixed to create a stream with small droplets, followed by further mixing to increase droplet size, facilitating effective salt transfer and separation in a desalter vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single mix valve is used to mix crude oil and water, then the mixing process is simple, but stable emulsions are formed that are difficult to break, reducing desalting efficiency
Solution Approach 1:
The single mixing stage is segmented into two distinct mixing stages: first mixing valve followed by a second mixing valve. This segmentation allows the first valve to create the initial emulsion for salt transfer while the second valve provides gentle mixing to optimize water droplet size distribution, preventing stable emulsion formation and improving desalting efficiency without excessive complexity
Solution Approach 2:
The first mixing valve performs preliminary mixing to create fine water droplets that facilitate salt transfer from crude oil to water. This preliminary action prepares the emulsion for the second mixing stage, where gentle mixing optimizes the droplet size distribution before separation, ensuring efficient desalting
2Quantity of substance
If high pressure drop is applied across the mix valve, then more salt is transferred to water, but smaller water droplets are formed that are difficult to separate, reducing dehydration efficiency
Solution Approach 1:
The mixing process is segmented into two stages with different pressure drops. The first mixing valve operates at high pressure drop to maximize salt transfer to water droplets. The second mixing valve operates at lower pressure drop to optimize water droplet size distribution, creating a balanced emulsion that facilitates both salt transfer and subsequent separation, thereby improving overall dehydration efficiency
Solution Approach 2:
The first mixing valve performs preliminary high-intensity mixing to ensure complete salt transfer from crude oil to water droplets. This preliminary salt transfer action is followed by a second gentle mixing stage that optimizes droplet size without compromising the salt transfer achievement, enabling efficient separation in the desalter
3Quantity of substance
If heavy crude oil is processed, then higher viscosity and density are present, but stable emulsions form that are difficult to break, making desalting more difficult
Solution Approach 1:
The processing of heavy crude oil is divided into two mixing stages. The first mixing valve creates fine emulsion for salt transfer despite high viscosity. The second mixing valve provides gentle mixing that optimizes water droplet size distribution in the viscous heavy crude, preventing overly stable emulsion formation and facilitating separation in the desalter, thereby improving desalting efficiency for heavy crude oils
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process improves desalting efficiency by increasing salt removal and reducing water carryover, thereby minimizing corrosion risks and enhancing energy utilization in refinery systems.
Implementation Method 1
mixing of the oil phase and the water phase is carried out using a single mix valve which creates the water and oil emulsion
Implementation Method 2
Within the desalter settling vessel, water droplets undergo coalescence under the influence of electrical and gravitational fields
Implementation Method 3
large water droplets settle down to the bottom of the desalter tank whereas smaller drops have a low settling velocity
Implementation Method 4
The oil and water are separated based on their density differences
Data Source
AI summary
A process and system for desalting crude oil includes delivering a stream of salty crude oil and wash water into a mixing valve, mixing the stream of salty crude oil and wash water through the mixing valve to create a mixed stream of desalted crude oil and salty wash water, delivering the mixed stream of desalted crude oil and salty wash water to a static mixer, and mixing the mixed stream of crude oil and wash water in the static mixer. Within the static mixer, the mixed stream is mixed in a coalescing regime to coalesce smaller droplets of water into larger droplets of water. The mixed stream is then directed to a desalter where the salty wash water is separated from the desalted crude oil.